Method of coating the inner surfaces of tubes



Anril 27 1926. 1,582,563

T. F. VON HAIMBERGER El AL mamov 0F comma THE INNER SURFACES 0F mans Filed July 20, 1922 Yaw M4, 41/ wig :32?

Patented Apr. 27,1926.

UNITED STATES PATE NT OFFICE.

'IHEODOR IREIHERR VON HAIMBEBGER, 0E GRUNEWALD, NEAR BERLIN, AND JOHANN KARL WIRTH, 9F GHABLOTTENBURG, NEAR BERLIN, GERMANY.

METHOD OF COATING THE INNER SURFACES OF TUBES.

Application filed July 20, 1922. Serial No. 576,376.

vTo all whom it may concern:

Be it known that we, THEODOR FREIHERR VON IIAiMBERGER and JoHAN KARL WIRTH, citizens of the German Republic, residing at Grunewald, near Berlin, Germany, and Charlottenburg, near Berlin, Germany, have invented certain new and useful Improvements in Methods of Coating the Inner Surfaces of Tubes, of which the following is a specification.

The present invention relatesto a method of and apparatus for producing insulating coatings or coatings capable of offering resistance on the inner walls of tubes of metal, metal fabrics 'or other materials. Such coatings may be produced for example by moistening the surface to be protected firstly with a phenol-formaldehyde condensation bestos or the like and then impregnating A the layer and furthertreating in a suitable manner 5 with a similar condensation uct.

"The employment of this mode of coating tubes offers considerable difficulties. Within prodthe tube to be coatedfiwhich is moistened with.

adhesive must be formed a new tube .of fibrous material which tube must adhere closely to the -adhesive-coated wall of the iouter tube While the adhesive must not be washed away, rubbed off or otherwise removed. These difficulties are still further increased by the fact-that in the formation of the coating of "fibre pulp or the like generally a portion of the liquid from the pulp is pressed out and this liquid must be led'ofi' without damaging the adhesive layer below. Moreover, care must be taken to avoid the formation of spaces between the tube and the coverin layer.

Apparatus for per ormance of the method is illustrated in-the accompanying drawing. The apparatus serving in a'cord-ance with this invention for producing coatings includes a supply pipe C which may either be stationary or may be rotated about its own axisjand connected with the feed hopper A.

. This pipe may be smooth but may-if it' is to beTo'tatetF-be provided with worm-like projections. Into the pipe C extends a mandesired at the end with worm-like projections and draining passages. A cover or stufling, box E is connected with the tube D to be coated by a screw thread or other easily detachable form of connection, the stufling box being formed at X with small air passages or holes. A braking device in the form of a weight, spring or friction producing device or the like (indicated diagrammatically in the drawing by a weight G connected with the cover) is provided. For rotating the mandrel F, there is a gearing O, driven by the intermediary of any suitablemeans (not shown) and a movable support H slidable on a bed K or the like, for correspondingf'o the longitudinal movement of the tube on the mandrel F. The modus operandi of the apparatus is as follows :-The adhesive liquid is applied to the tube D to be coated on' the inside and to the supply pipe C on the outside whereupon the tube D is pushed over the pipe C. By applying adhesive liquid to the supply pipe 0 the danger of removal of the adhesive layer in sliding the tube D over the pipe G, is avoided. If desired, during the pressing operation, adhesive liquid may be supplied to the space between the tubes D and C from Y. i

The tube D to be coated is now closed by thecover E, and the mandrel F .is brought into the correct position and either secured or set-in rotation about its longitudinal axis which coincides with the longitudinal axis of the supply pipe 0.

Moist asbestos pulp or the like from the feed hopper A is forced by means of the conveying worm B or by other suitable device through the supply pipe G against the mandrel F. The cover E takes/the pressure.

' The braking device, shown in the drawing like is now forced orpushedinto the s ace Z between the point of the mandrel an the pipe C until suflic'ient cohesion of the fibres and firm adhesion to the walls of the tubeD is attained. .Usually a portion of the liquid from the fibre ulp is' pressed out. This" liquid may be-led off through small channels at the end of the mandrel and can be drawn through alcollector in the centre'ofthe man-- .drel. During the positive forward motion of the tube D the whole internal wall is covered homogeneously with the layer formed from the fibre pulp without damaging the layer of adhesive.

After these operations the tube is subjected to its further treatment.

In the performance of the method there may be used as an adhesive and impregnating medium, in addition to the condensat1on products of phenol and formaldehyde, other suitable materials, for example Waterglass solutions, solutions of natural and artificial resins, solutions of celluloid, acetylcellulose, caoutchouc etc. To produce the coating there may be used in addition to fibrous materials, granular materials as for example quartz sand not too fine, fire-clay powder and so on. In this case the liquid of the pulp is preferablytreated with some binding medium in order that after drying the inner layer produced will still remain porous but will hold together sufiieiently so as not to break up during the subsequent impregnation.

lVhat we claim is 1. A method of coating tubes with resisting substances, comprising, first coating a tube with a layer of adhesive material, then putting the coated tube telescopically over a supply conduit and a mandrel, then pressing a fibrous covering material through the supply conduit and into the hollow space between tube and mandrel to thereby slide the tube longitudinallyover the mandrel, and supplying a resistance to the sliding of the tube.

2. A method of coating tubes with resisting substances, comprising, first coating 40 a tube with a layer of adhesive material, then puttin the coated tube telescopically over a supply conduit and a mandrel, then pressing a fibrous covering material through the supply conduit and into the hollow] space between tube and mandrel to thereby slide the tube longitudinally over the mandrel supplying a resistance to the sliding of the tube, and-permitting the escape of liquid from the fibr'ous covering material.

3. A method of coating tubes with resisting substances, comprising, first coating a tube with a layer of adhesive material, then putting the coated tube telescopically over a supply conduit and a rotating mandrel, then pressing a fibrous covering material through the supply conduit and into the hollow space between tube and mandrel to thereby slide the tube longitudinally over the mandrel, and supplying a resistance to the sliding of the tube. V

4. Apparatus for coating the inner wall of tubes, comprising a feed hopper for feeding the covering material, a supply conduit connecting with said feed hopper, a pointed end mandrel positioned in the longitudinal axis of the supply conduit and extending into the same with its ointed end, a slidable stufiing box positione on the mandrel and braking means for regulating movement of the stufiing box relative to the said supply conduit.

5. Apparatus according to claim 4 said stutfin box being adapted to receive one end oi a tube to be coated, and the supply conduit to receive the other end of the tube to be coated.

6. Apparatus according to claim 4 there being drain passages between the said mandrel and stufiing box.

7 A method of coating the inner wall "of adhesive coated tubes with a covering material adatpted to be attached thereto by means 0 ing an adhesive to the inner wall of a tube, pressing the covering material through a supply. conduit sleeved by the adhesivecoated tube against a mandrel, thereby forcing said tube forward by the pressure of the covering material passing between the mandrel and the tube againsta resistance.

In testimony whereof we afiix our signatures.

Dipd. lug. THEODOR FREIHERR von HAIMBERGER. Dipd. In 10. KARL WIRTH.

the adhesive, comprising, apply- 

